We are interested in studying the interaction of skin microorganisms with body secretions as it relates to axillary and scalp odors. We wish to correlate the presence or absence of specific volatile metabolites (odors) with cutaneous microorganisms in both in vivo and in vitro studies. A preiminary study has been made of the chemical nature of apocrine secretion. Analysis of the odorants generated on heating of apocrine secretions led to the identification of two androgen steroids which may play a role in the development of axillary odors. Odors specific to axillary skin microorganisms are formed by incubation of the organisms on apocrine secretion. A technique for analysis of volatile metabolites has been developed which involves their concentration on an organic polymer and their subsequent separation and identification by gas chromatography-mass spectroscopy. This approach has been successfully utilized for the determination of an in vitro odor profile for several microorganisms including a scalp yeast on a lipid-rich substrate. We wish to investigate the use of such odor profiles as additional aids in the classification of microorganisms. An understanding of the interaction of skin microorganisms and body secretions should provide alternate methods of odor control and of disease diagnosis in cases which involve changes in body odors.